7125 ‎(2)‎

• UCREFRP Catalog Number: 7125
• Author: McAda, C. W.
• Title: Aspects of the Life History of Three Catostomids Native to the Upper Colorado River Basin.
• USFW Year: 1977.
• USFW - Doc Type: Utah State University,
• Copyright Material: YES

2
for designation as "endangered" and "threatened" respectively by the
Desert Fishes Council in 1975 [Personal communication, G. C. Kobetich,
U. S. Fish and Wildlife Service, Las Vegas, Nevada].
The fish fauna of the Colorado River basin is unique because 74%
of the native fish are endemic to the basin [Miller, 1958]. All of
the endemic species still remain in the upper basin, but most of the
large-river fish have been eliminated from the lower basin [Minckley,
19731. Expansion-of water development in the upper basin now
jeopardizes the remaining habitat of the native fish. Dams have been
proposed for the upper Colorado River and its tributaries that may
cause the extinction of some native forms. In addition, water from
the basin will play a vital role in the extraction of energy resources
(e.g., oil, oil shale, coal and uranium) that are found in this area
of the western United States. The added demands will further reduce
the quality and quantity of water in the basin.
The introduction of exotic species is also believed to have a
detrimental impact on the native fauna [Miller, 1961]. Holden and
StaZnaker [1975x] recorded 10 native fish species (35%) and 19
introduced species (65%) in the main stems of the upper Colorado River.
Alterations-of the river environment have produced a favorable
environment for exotic species, which have become so numerous that
competition for food and space may be a major factor in the decline
of native fishes [Miller, 1961; Minckley and Deacon, 1968; Minckley,
1973; Holden, 1973]. SeethaZer, McAda and Wydoski [1977] outlined
many of the factors involved in the decline of the native fish fauna.
Holden and Stalnaker 11975a] believed that the Yampa River in
northwestern Colorado plays a vital role for the continued existence